1. Field of the Invention
The present invention pertains to lighting fixtures, and more particularly to adapters and other fixtures for holding fluorescent and other non-incandescent lamps and allowing such lamps to be operated on line voltage supplied, e.g., by an incandescent light socket.
2. Description Of The Related Art
It is well known that many lamps exist which have a higher light-generating efficiency than incandescent bulbs. For example, fluorescent lamps, magnetic or solid state halogen lamps, and magnetic or solid state H.I.D. lamps each generate more light for a given consumption of power than do incandescent bulbs. Nevertheless, the use of incandescent light sockets prevails in most existing buildings and incandescent light sockets continue to be installed even in many newly-constructed buildings. Thus, an adapter which allows different lamps to be operated from an incandescent light socket is desirable from the view point of economy.
Adapters which allow fluorescent lamps to be operated from an incandescent light socket are known. One type of fluorescent lamp used with such adapters is of an elongated U-shape, the base of the lamp having a pair of electrical pin connectors, one on either side of a depending starter housing. Adapters for this and other types of fluorescent lamps have a screw-type socket base for insertion into an incandescent socket, and contain pin receptacles for accepting the pin connectors of the fluorescent lamp. A ballast or solid state regulation circuit is provided in the adapter to control current in a well known manner, and may be annular in shape and mounted so as to surround some portion of the lamp when the latter is received in the adapter.
However, the characteristics peculiar to an incandescent application place operational constraints on the fluorescent adapter, and have heretofore limited the power rating or maximum wattage of the fluorescent lamp. This limitation is directly traceable to the heat generated during operation of the fluorescent lamp in the adapter.
Heat is generated both by the fluorescent lamp and by the ballast (or regulation circuit) within the adapter. The lamp generates heat due to power losses during the generation of light. An inductive ballast generates heat due to power losses caused by eddy currents induced in the metal core of the ballast by changing magnetic flux. While the core of such a ballast is normally laminated to interrupt these eddy currents, power losses in the ballast core are nevertheless substantial and result in significant heat generation. Similarly, power losses in regulation circuits (e.g., I.sup.2 R losses) result in significant heat generation.
Thus, heat generated by the fluorescent lamp and adapter places an upper limit on the maximum power rating of the fluorescent lamp which can be used practically in a standard incandescent fixture. Moreover, heat generated even in practicable applications can limit the life of both the fluorescent lamp and the adapter by contributing to the breakdown of these items.
The physical arrangement of the adapter in particular applications can also further exacerbate the problems caused by excessive heat. It may be desired to use such an adapter in a ceiling fixture such as the type known as a "high hat". In such an application, the adapter would be placed at the top of a reflector arranged to direct light down into a room. The internal physical dimensions of the reflector limit the size of an adapter which may be utilized and the adapter must therefore be designed to make efficient use of the space available within the high hat. Heat generated by the adapter and the lamp is therefore confined and concentrated at the upper portion of the reflector, precisely where the adapter is located. The heat has a direct and severe impact on the proper operation of the adapter, and limits both the power rating of the fluorescent lamp and the life of the lamp and the adapter.
These and other drawbacks of excessive heat within a fluorescent, or other, lamp assembly are overcome by my invention.